1. Field of the Invention
The present invention relates to a bolt setting tool for driving bolts and similar fastening elements into constructional components and including a bolt guide having a receiving chamber, an axially displaceable drive piston having a head, a sleeve-shaped pressure member arranged between the head of the drive piston and the bolt guide and having a cylindrical extension extending in a setting direction and projecting into the receiving chamber of the bolt guide, with the cylindrical extension having a smaller diameter than a remainder of the pressure member and an elastic pad mounted on the cylindrical extension of the pressure member.
2. Description of the Prior Art
There exists a number of different bolt setting tools for driving bolts or the like into constructional components and including a reciprocating drive piston. The energy for effecting the drive-in can be obtained, e.g., from explosive powder charge-containing cartridges. The primary energy of the ignited cartridge is transformed into the kinetic energy of the drive piston which drives a bolt or the like into a constructional component. With only a partial use of the kinetic energy of the drive piston, the excess energy must be absorbed without any damage to the movable parts of the tool. Because, as is known, the constructional components have very different consistencies or rigidity properties, the bolt setting tool should be designed with a relatively high reserve of excess energy. The components of the setting tool, which cooperate with the drive piston, can be seriously damaged as a result of being subjected to a high energy impact by the drive piston. That would require their replacement, resulting in additional expenses and an increased idling time.
There essentially exist two possibilities to deal with an excess energy in bolt setting tools equipped with a drive piston. In the first case, the excess energy is dissipated outside of the setting tool. To this end, the tool is so designed that the drive piston exits the mouth of the tool and becomes operatively connected with a constructional component into which a bolt or other fastening element is being driven in. With a normal rigidity of the constructional component, the excess energy is dissipated as a result of partial penetration of the drive piston in the constructional component or a constructional part. Thus, the drive piston performs a deformation work outside of the setting tool. With these constructive measures, the run-on shoulders or the like inside the tool are loaded to a small extent only. However, with these constructive measures, the bolt setting tool looses its advantage of achieving a uniform penetration depth of the bolts independently from the rigidity characteristics of a constructional part or component. Rather, the opposite is the case. The penetration depth of the bolt would vary dependent on the rigidity of the components. With a weak constructional part, this can result in a driven-in bolt emerging form the rear side of the constructional part.
In the second type of the setting tools, the excess energy is absorbed or dissipated between the elements of the setting tool itself. The absorption of the excess energy is achieved by providing plastically or elastically deformable parts between two, movable relative to each other, tool elements. Thus, German Publication DE-A-1 478 838 discloses a bolt setting tool in which a sleeve-shaped pressure member, which is operatively connectable with the drive piston, and an excess energy-absorbing pad are arranged between the drive piston and the bolt guide. The pad is mounted on a smaller diameter extension of the stepped pressure member and is supported against a shoulder of the pressure member facing in the setting direction and an annular matching surface of the bolt guide facing in a direction opposite the setting direction. Because the pressure member is displaceable relative to the bolt guide, a relatively large clearance is provided between the two parts. As a result, on opposite sides of the pad, annular clearances or gaps are present between the pressure member and the bolt guide. Upon compression of the pad, it can wedge between the inner wall of the bolt guide and the outer wall of the pressure member. This can result in jamming of the movable parts which may cause a breakdown of the tool.
Accordingly, an object of the present invention is to provide a bolt setting tool in which the excess energy is absorbed within the tool and in which jamming of the movable parts is reliably prevented.
Another object of the present invention is to provide a bolt setting tool in which the possibility of jamming of movable parts is eliminated and the constructive elements have a simple structure and can be easily mounted in the tool.
A further object of the present invention is to provide jamming preventing means which can easily be installed in the existing setting tools.